Preparation of unsymmetrical thiol-allene diadducts

ABSTRACT

UNSYMMETRICAL THIOL-ALLENE DIADDUCTS (1,3-AND 1,2-BIS (SUBSTITUTED MERCAPTO)-PROPANES) ARE PREPARED BY THE FREE RADICAL AND/OR IONIC ADDITION OF A THIOL COMPOUND TO A MONOADDUCT ALLYL SULFIDE OR THROUGH THE SEQUENTIAL ADDITION OF TWO DIFFERENT THIOL COMPOUNDS TO ALLENE. DIADDUCTS CONTAINING A DIALKYL DITHIOPHOSPHORIC ACID CONSTITUENT AND EITHER AN ALKYL OR ARYL THIOL CONSTITUENT ARE EFFECTIVE AGRICULTRUAL CHEMICALS.

United States Patent Oflice 3,591,475 Patented July 6, 1971 3,591,475PREPARATION OF UNSYMMETRICAL THIOL-ALLENE DIADDUCTS Karl Griesbaum,Forchheim, Germany, and Alexis A. Oswald, Mountainside, and Daniel NoyesHall, Linden, N.J., assignors to Esso Research and Engineering Com- P yNo Drawing. Continuation-impart of application Ser. No. 368,351, May 18,1964, now Patent No. 3,340,332. This application Dec. 9, 1968, Ser. No.782,466

Int. Cl. B011 1/10; C07c 149/06, 149/26 U.S. Cl. 204158R 19 ClaimsABSTRACT OF THE DISCLOSURE Unsymmetrical thiol-allene diadducts [1,3-and 1,2-bis (substituted mercapto)-propanes] are prepared by the freeradical and/or ionic addition of a thiol compound to a monoadduct allylsulfide or through the sequential addition of two different thiolcompounds to allene. Diadducts containing a dialkyl dithiophosphoricacid constituent and either an alkyl or aryl thiol constituent areeffective agricultural chemicals.

CROSS REFERENCE TO RELATED APPLICATION This application is acontinu'ation-in-part of Ser. No. 368,351, filed May 18, 1964, now U.S.Pat. 3,340,332.

BACKGROUND OF THE INVENTION (I) Field of the invention This inventionrelates to new processes for the preparation of unsymmetricalthiol-allene diadducts and to the utilization of the products producedwith the processes as pesticidal compositions. More particularly, thisinvention relates to the synthesis of unsymmetrical 1,3- and l,2-bis-(substituted mercapto)-propanes by the addition of an organic thiol to amonoadduct allyl sulfide or by the sequential addition of differentthiols to allene. Products of the processes find particular utility asinsecticides, miticides and nematocides.

(II) Description of the prior art Compounds related to the unsymmetrical1,3- and 1,2-bis-(substituted mercapto)-propanes produced with thepresent process namely, 1,2-bis(substituted mercapto)- ethanes, havebeen prepared by the prior art workers. The prior art unsymmetricalethane compositions were conventionally prepared using simpledisplacement reactions involving either an alphaor betachloroalkylsulfide with the thiol salt. The unysmmetrical ethane compositions werealso prepared by reacting a metal sulfide with an alkyl halide. Theabove described processes are set forth in detail in U.S. 2,759,010,U.S. 2,793,224, U.S. 2,976,311 and U.S. 3,004,980.

SUMMARY OF THE INVENTION In accordance with the present invention,unsymmetrical thiol-allene diadducts are formed by (a) the addition of aspecific thiol reagent to a monoadduct allyl sulfide or (b) thesequential addition of different thiols to allene. The hydrogen donorabilities of the thiols employed in the processing step are an importantfeature of the invention, in that, hydrogen donor ability is critical tothe selection of the thiol compound that is added to a monoadduct allylsulfide and, in the case of additions to allene, the order of additionof the different thiols is dictated by the respective hydrogen donorabilities with thiol of lower ability being added first. Theunsymmetrical products of these reactions, particularly those compoundsthat are prepared utilizing a dialkyl-dithiophosphoric acid as one ofthe thiol reactants, possess properties that makes them suitable for useas agricultural chemicals.

The free radical type reactions contemplated by this invention may berepresented as follows:

RSCH CH=CHz R H2)aSR Equation I illustrates the reaction of a thiolcompound with a monoadduct allyl sulfide to form an unsymmetricalthiol-allene diadduct. Equation II shows the sequential addition of twodiffering thiols to allene in order to arrive at the unsymmetricaldiadduct product. The intermediate material of Equation II is identicalto the starting material of Equation I. As will be noted more fullyhereinafter, the thiol reactant employed in Equation I (RSH) preferablyhas a higher hydrogen donor ability than the thiol (RSH) correspondingto the RS- radical of the monoadduct allyl sulfide starting material. InEquation 11 the thiol reactant having the lower hydrogen donor ability(RSH) is preferably added in the first step of the overall reaction.

The second addition step involving the reaction of the thiol compoundwith the allyl sulfide can be also carried out via an ionic mechanismyielding unsymmetrical 1,2- bis(substituted mercapto)-propane diadducts.The reactions contemplated proceed as follows:

RSH CH =C=CHg RSH RS-CH2CH=CHZ The ionic additions again preferablyinvolve the use of a thiol compound (RSH) of higher hydrogen donorability in the final portion of the overall reactions. The ionicaddition reactions proceed at higher rates at elevated hydrogen ionconcentration. The higher rate of the reaction is believed to beexplained by the following mechanism:

H+ RSH RSCH 'CH=CHz RSCH2CHCH3 RSCH2CHSR' If the thiol reactant (RSH) istoo weak an acid and, therefore, is unable to provide the concentrationof hydrogen ions necessary for a significant reaction rate, the reactionmay be promoted by the addition of strong acid catalysts, such asperchl-oric acid, sulfuric acid, boron trifluoride, toluene sulfonicacid and methane sulfonic acid. The acid catalysts may be used inconcentrations ranging from 0.2 to 20 mole percent preferably 0.5 to 5mole percent, based on total reactants. The reaction rate of the ionicadditions is also strongly affected by the reaction temperature. Byraising the reaction temperature practical reactant conversions may bereached without the addition of extra acid catalysts.

The ionic and the free radical addition to allyl sulfides may occurconcurrently. If a free radical type addition is desired, a free radicaltype catalyst is employed and the reaction is carried out at relativelylow temperature where the rate of the competing ionic reaction becomesinsignificant. To obtain high yields of the ionic-type product, it maybe necessary to add a free radical inhibitor to suppress the radicaltype reaction. Useful inhibitors include sulfur, alkylphenols,hydroquinone, phosphorus sesquisulfide, etc. The presence of aninhibitor may be important when elevated reaction temperatures are usedsince heat and/or oxygen may also initiate a free radical type reactionin the absence of inhibitors.

The RSI-I and RSH reactants that are employed in the above reactions aredifferent members of the group of compounds wherein R and R aremonovalent organic radicals containing 1 to 30 carbon atoms which may bedefined as follows:

R and R are C to C preferably C to C alkyl groups, e.g., methyl, ethylsecondary butyl, 2-ethylhexyl, n-decyl, tertiary-dodecyl,nonylhexadecyl, nonyloctadecyl, etc.;

R and R are C; to C preferably C to C cyclic groups, containing at leastone oxygen, sulfur or nitrogen atom, for example, benzothiazyl, pyridyl,furfuryl, thiazyl, thienylmehtyl, pyrryl, pyranyl, etc.;

R and R are C to C preferably C to C aryl or haloaryl groups, e.g.phenyl, naphthyl, halophenyl,

chlorophenyl, trichloronaphthyl, etc.;

R and R are C; to C preferably C to C alkylaryl groups, e.g.,nonylphenyl, xylyl, dodecylphenyl, tolyl, diethylnaphthyl,octadecylphenyl, etc.;

R and R are C to C preferably 0, to C arylalkyl groups, for example,benzyl, phenylisopropyl, naphthylmethyl, ethylbenzyl, trimethylbenzyl,etc.;

R and R are C, to C preferably C to C non-hydrocarbon substituted alkylgroups, for example, aminoethyl, hydroxyethyl, cyanoethyl,mercaptoethyl, carboxyethyl, chloroethyl, carbomethoxyethyl,carbolauryloxypropyl, carbolauryloxyethyl, carbooctadecyloxyethyl, etc.;

R and R are C to C preferably C to C non-hydrocarbon, non-halogensubstituted aryl or alkylaryl groups, for example, hydroxyphenyl,nitrotolyl, aminophenyl, methylthiophenyl, ethylsulfinylphenyl,cyanotolyl, nitronaphthyl, etc.;

R and R are acyl radicals having the structural formula:

wherein Z is a C to C preferably, a C to C hydrocarbyl radical, forexample, alkyl radicals, alkenyl radicals, aryl radicals or alicyclicradicals and most preferably a lower alkyl radical such as a C to Calkyl radical; and

R and R are dihydrocarbyloxythiophosphoryl or dihydrocarbyloxyphosphorylgroups having the structure:

wherein Y is a sulfur or oxygen atom, preferably a sulfur atom, X and Xare C to C preferably C to C hydrocarbyl radicals, for example, alkylradicals, alkenyl radicals, aryl or alicyclic radicals; most preferablyX and X are C to C lower alkyl groups. Representative examples of usefulthiol acids, monothiophosphoric acids and dithiophosphoric acids includethiolacetic acid, thioldodecanoic acid, thiolbenzoic acid, thiolcrotylicacid, thiolcyclohexane carboxylic acid, diethyldithiophosphoric acid,dimethylmonothiophosphoric acid, diphenylmonothiophosphoric acid,dioctylphenylthiophosphoric acid, etc.

The thiol reactants used in the present process are selected in such amanner that the R and R groups of the desired unsymmetrical diadductproduct are different substituents.

The preferred RSH reactants are the above-describeddihydrocarbylthiophosphoryl materials wherein X and X are C to C alkylgroups used in conjunction with C to C alkyl thiols such as methanethiol or C to C aryl thiols and haloaryl thiols such as benzenethiol,p-chlorobenzenethiol, bromobenzenethiol or dichlorobenzenethiol. Thesereactions are preferred as they lead to the produc- 4 tion ofunsymmetrical diadducts having the structural formula:

wherein A are alkyl, aryl or haloaryl groups of the types previouslydefined. These latter compounds have been found to have desirablepesticidal properties.

The 1,3-bis-(substituted mercapto)-propanes are highly effectiveagricultural chemicals. The subject materials are markedly superior toknown substituted mercapto ethanes and methanes both in pesticidalactivity and toxicity toward warm blooded animals. This activity issurprising in view of the relative biological inactivity ofgammachloroalkyl sulfides when compared to the beta-chloroalkyl sulfides(mustards).

It has been found that due to the nature of the process reactants andthe reactions themselves, the free radical reaction for the formation ofthe diadducts may result in the formation of symmetrical diadducts inpreference to the desired mixed or unsymmetrical diadducts. Symmetricaldiadduct formation is generally due to a phenomenon known as allylicreversal. It has now been discovered that the tendency to form thesymmetrical diadduct is dependent upon the relative hydrogen donorability of the thiol reactants. Hence, using a thiol (RSH) that has ahigher hydrogen ability than the thiol (RSH) corresponding to theRC-radical of the starting or intermediate monoadduct allyl sulfide iscritical to the formation of good yields of the preferred mixed orunsymmetrical diadduct. When the monoadduct allkyl sulfide is securedthrough the reaction of a thiol with allene, the thiol sulfide shouldhave the superior hydrogen donor ability of the two thiol reactants. Incase the thiol reactant used in the second step of Equation II hasinferior hydrogen donor ability, large amounts of the correspondingsymmetrical 1,3-bis- (substituted mercapto)-propanes are formed.

The relative hydrogen donor ability of a particular thiol reactant maybe determined by reference to the chemical literature on chain transferconstants in polymerization reactions since the chain transfer constantis directly proportional to hydrogen donor ability. One method ofdetermining chain transfer constants for thiols is described by J. L.OBrien and F. Gornick, J. Am. Chem. Soc. 77, 4757 (1955). This methodinvolves a mathematical determination of the chain transfer constantfrom data on monomer and thiol concentrations and degree ofpolymerization in a free radical initiated polymerization reaction.Alternatively, hydrogen donor ability may be measured by the ease withwhich 2-cyano-2-propyl radicals will abstract hydrogen from RSH asdetermined by the yield of RSSR dimer which is produced by combinationof the thiyl radicals after hydrogen abstraction. This latter method ismore fully described by P. Bruin et al., Recueil, 71, 1115 (1952).

The reactions contemplated by the process of this invention (Equations Iand II) involve free-radical reactions between monoadduct allyl sulfideand a thiol and between allene and a thiol. Such free-radical reactionsare typically carried out in the presence of a free-radical initiator,particularly, a chemical initiator or radiation. Examples of radiationfree-radical initiators include ultraviolet light, gamma radiation,heat, etc. Useable chemical initiators include peroxidic and azocompounds such as cumene hydroperoxide, tertiary butyl hydroperoxide,bistertiar butyl peroxide, bis-azo-isobutyronitrile, dicumyl peroxide,benzoyl peroxide, etc. The various types of freeradical initiators maybe employed alone or in combination with each other, e.g. a combinationof ultraviolet light and an azo or peroxide compound. Typically, chemical initiators are used within the reaction zone at levels ranging from0.01 to 10, preferably 0.1 to 3 mole percent based on thiol reactant.

A wide range of reaction conditions may be employed in the process ofthis invention. Reaction temperatures suitable for both the formation ofthe monoadduct allyl sulfide from a thiol and allene and the freeradical reaction of a monoadduct allyl sulfide with a further thiol fallin the range of from 100 to 50 C., preferably 40 to 100 C., mostpreferably at temperatures from to 50 C. Reaction temperatures for theionic reaction of the monoadduct allyl sulfide with a further thiol mayalso range from 100 to +150 C. However, it is preferable that thesereactions be carried out between 0 to 150 C., most preferably attemperatures exceeding 50 C.

It is desired that the reaction be conducted in the liquid phase; hence,pressure within the reaction zone is adjusted to maintain liquid phaseconditions. In the production of monoadducts starting with the lowboiling allene, higher pressures are used. Reaction pressure is not acritical variable in the process and depending upon other processconditions superatmospheric as well as atmospheric pressures may beemployed. Typical reaction pressures vary in the range of from 0 to 750p.s.i.g. and preferably from 14 to 150 p.s.i.g., e.g., 50 p.s.i.g. Thereaction period can also vary over a wide range. The reaction time isstrongly dependent upon the nature of the process reactants, type ofcatalyst, temperature and pressure conditions, etc. Hence, appreciableyields of the desired unsymmetrical diadducts can be secured in timeperiods varying from a few minutes to several days.

The instant reactions may be carried in bulk, that is, in the absence ofa solvent or in the presence of an inert organic diluent that does notenter into or interfere with the reactions. Hydrocarbons, chlorinatedhydrocarbons, ethers, thioethers, etc., can be used. Examples of usefuldiluents include cyclohexane, cyclooctane, benzene, toluene,tetrahydrofuran, diglyme, etc. The ratio of the process reactants tosolvent is not critical and may vary over a wide range. Unless theprocess reactants are solid materials, it is preferable to avoid usingsolvents because their presence serves to (a) introduce separationproblems into the process and (b) reduce reactant concentration duringreaction thereby diminishing process efiiciency. In situations wheresolvents are employed, at least about 10 volume percent of solvent,based on total reactants, is used.

The relative ratio of process reactants within the reaction zone is acritical feature of this invention. The reaction involving the additionof a thiol of relatively low hydrogen donor ability to allene must becarried out under conditions that favor the formation of the monoadductallyl sulfide product. It is possible to form a symmetrical thiol-allenediadduct during this step. The formation of the allyl sulfide monoadductis favored by having a molar excess of allene present within thereaction zone. It is desirable to have at least about 1.2 moles ofallene present Within the reaction zone per mole of thiol. Preferably,the molar ratio of allene to thiol should be maintained in the range of2:1 to 10:1 and most preferably between about 3:1 to 5:1. Furtherinformation concerning the formation of monoadduct allyl sulfides iscontained in US. Ser. No. 368,345, filed May 18, 1964, now Pat. No.3,398,200, which disclosure is herein incorporated by reference.

The reaction for the formation of the unsymmetrical thiol-allenediadduct does not require the use of excess process reactants within thereaction zone; however, product formation has been found to be favoredby employing a molar excess of the thiol reactant relative to themonoadduct allyl sulfide. Desirably, about 1.2 moles of thiol reactantis utilized per mole of monoadduct allyl sulfide. Preferably, molarratios of thiol to monoadduct allyl sulfid'e in the range of 3:2 to :1and more preferably between 3:1 and 5:1 may be employed. The higher thehydrogen donor ability of the thiol, the less thiol excess is necessaryfor a high yield of the desired unsymmetrical products.

In the formation of unsymmetrical adducts by the sequential addition oftwo dilferent thiols to allene, intermediate monoadduct allyl sulfideshould, in general, be separated from the unreacted thiol employed inthe first stage operations prior to contacting the same with the thiolof higher hydrogen donor ability. If the first thiol is not separatedfrom the monoadduct allyl sulfide, the possibility exists thatselectivity to the desired unsymmetrical product may be diminished inthe second portion of the operation. Typically, the reaction productfrom the reaction of a thiol with a monoadduct alkyl sulfide conductedusing a thiol having a hydrogen donor ability superior to the hydrogendonor ability of the thiol corresponding to the SR radical of themonoadduct allyl sulfide contains at least about 50 mole percent of thedesired mixed diadduct. In most instances, the crude reaction productcontains at least about to mole percent of the unsymmetrical diadduct.

While the invention has been described with respect to a preferredtwo-step reaction involving the addition of a thiol to allene in thefirst step, it will be understood by those skilled in the art that thepreparation of the monoadduct may be carried out by any conventionalmethod known in the prior art. The manner of preparing the monoadduct islimited only by the structure of the desired di-adduct, i.e., the thiylgroup of the monoadduct must be of lower hydrogen donor ability than thethiyl group to be added in the free-radical addition to form thedi-adduct.

As noted earlier, a number of products formed with the instant processfind utility as agricultural chemicals. Products of the process havemany other different uses. For example, the unsymmetricalthiol-thiophosphoric acid adducts can be used as animal health agents,e.g., for controlling animal parasites. The thiol-mercaptopropionicester adducts are elfective stabilizers for polyolefins such aspolypropylene plastics. The unsymmetrical adducts are also antioxidantand anticorrosion agents and as such can be used as additives forhydrocarbon oils such as mineral oil lubricants.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be furtherunderstood by reference to the following illustrative examples.

EXAMPLE 1 A mixture of 5.5 grams (0.05 mole) of benzenethiol and 5.1grams (0.05 mole) of allyl ethyl sulfide was irradiated with ultravioletlight in a quartz tube at 20 C. for 6 hours. Analysis of the reactionmixture by gasliquid chromatography and nuclear-magnetic resonancespectroscopy showed that the mixed diadduct, l-ethylmercapto3-phenylmercaptopropane constituted 89 mole percent of the productmixture. The other identifiable reaction products were allyl phenylsulfide and 1,3-bisphenylmercaptopropane.

In a series of reactions identical to that described above, allyl ethylsulfide was reacted with n-propyl mercaptan, isobutyl mercaptan andtertiary butyl mercaptan. The results are summarized in Table I.

J. OBn'en and F. Gornick, J. Am. Chem. Soc. 77, 4757 (1955). 2CHaCHzCI-IgCHgSH has a constant of 0.66.

These results show that the reaction selectivity towards the mixeddiadduct increased with the hydrogen donor ability of the second thiol(R'SH) as measured by chain transfer data for thiols taken from theliterature. The mixed diadducts, i.e., 1,3-bis-(substitutedmercapt0)-propanes, were isolated by fractional distillation. As shownin Table II, the physical and analytical data of the products confirmedtheir structure.

in a quartz tube for 6.5 hours at 12-15 C. Gas liquid chromatography ofthe product showed that 60% conversion occurred and that 95 mole percentof the product Physical and Analytical lmta of 181315 \Substitutt-(lMcrcapto) lropancs Formula B.P Calculated, Percent Found, percentStructural Empirical C mm C II S (7 H S CzH S(CII2) SPI1 s 110 121 1. .362. 35 T. 60 30. 63. 56 7. 63 29. 78 C H S(CH1) S(CH )1( II T! 73 0. .553.111 10.18 255.01 53. 81 10. 05 35. 31 C;II5S(CIL)1S( 11(C1l1): 53- 59u. 41 10. 18 35.01 53. 6O 0. 215 36.14 C;H S(CI1;) SC(CI13)3 58 71 0. 6556. 22 10. 40 29 56. .26 10.55 33. 49

The preparative and isolation techniques used for the preparation andrecovery of the above compounds are described below with reference tothe synthesis of lethylrnercapto-3-phenylmercapto-propane. In thereaction a mixture of 110 g. (1 mole) of benzenethiol and 20.4 g. (0.2mole) of allyl ethyl sulfide were irradiated for 12 hours at 17 C.N.m.r. analyses of samples (a total of 7.9 g.) withdrawn during thereaction showed that the reaction was essentially complete after 4hours. The reaction mixture was diluted with ether, extracted with 10%aqueous sodium hydroxide, washed with water, and dried over anhydroussodium sulftae. After removal of the solvent at atmospheric pressure,the remainder was distilled in vacuo to give two fractions. 3.6 g., B.P.99-l2l (1.2 mm.), and 29.6 g., B.P. 121 (1.2-4.5 mm.), respectively. Thefirst fraction was shown by g.l.p.c. to be substantiallyl-ethylthio-3-phenylthiopropane contaminated with a material of similarretention time (possibly a 1,2- isomer). The second fraction was thepure unsymmetrical 1,3-diadduct. The distillation residue (3.0 g.) wasfound by n.m.r. to contain about 70% of this compound and 30% phenyldisulfide. The overall yield was, therefore, 89% of theory.

EXAMPLE 2 A mixture of 1.2 g. (0.02 mole) of ethanethiol and 3.0 g.(0.02 mole) of allyl phenyl sulfide were irradiated with U.V. light for385 minutes at l7-20 C. Analysis by gas-liquid chromatography showedthat the product mixture contained only 6 mole percent of the 1,3-mixeddiadduct, 1 ethylmercapto 3-phenylmercapto-propane. The overallconversion of the reaction was with the other products being ethyl allylsulfide. 1*,3-bis-(ethylmercapto) propane and 1,3 bis (phenylmercapto)-propane.

Similar experiments were carried out adding ethanethiol to n-propylallyl sulfide, isopropyl allyl sulfide and tertiary butyl allyl sulfide.The mole percent of the mixed diadduct in the product mixture in eachcase is shown in Table III.

TABLE III Mole percent mixed diadduct RS: in product mixture PhS 10 CHCH CH S 63 (CH CHS- 71 (CH CS 76 Comparison of Tables I and III showsthat the order in which two different thiols are added to allene canhave an effect on the overall yield of mixed diadduct. The elfect isgreat when the structures of the two thiols are very different, e.g.,ethanethiol and benzenethiol. The effect is negligible with two thiolsof very similar structure, e.g., n-propanethiol and ethanethiol. Forpractical use these results show that the poorer hydrogen donor of twothiols should be added first to allene to form an allyl sulfide.

EXAMPLE 3 A mixture of 2.2 g. (0.02 mole) of benzenethiol and 1.02 g.(0.01 mole) of allyl ethyl sulfide was irradiated Ill) TABLE IVReact-ant, moles Allyl Reactant Selec- BOHZUIIP vthyl molar tivity tothiol sulfide ratio diadduct EXAMPLE 4 A mixture of 30.6 g. (0.3 mole)of distilled allyl ethyl sulfide and 67 g. (0.36 mole) of distilleddiethyl dithiophosphoric acid was placed in a quartz reaction tubeequipped with a magnetic stirrer and placed within a water baththermostated at 15 C. The reaction mixture was then irradiated with a 75watt Hanau immersion lamp emitting a wide spectrum of ultravioletirradiation from a high pressure mercury arc. The progress of theirradiation initiated reaction was followed by nuclear magneticresonance (n.m.r.) spectroscopy of samples taken periodically from thereaction mixture. On the basis of the disappearance of the olefinichydrogen signals, it could be estimated that the allyl sulfide reactantconversion was 25,141, 62 and 82% after /2, 2, 8 and 24 hours, respecuvey.

The crude reaction product was diluted with 300 milliliters of ether andwas washed twice with 85 milliliter portions of 5% aqueous sodiumhydrogen carbonate solution to remove the unreacted acid. The neutralether phase was then separated and dried over 25 q. of anhydrous sodiumsulfate. The dry solution was then fractionally distilled.

After the removal of the ether and the unreacted allyl ethyl sulfide,the reaction product was distilled at a pressure of 0.1 millimeter ofmercury between 126- 127 C. and a slightly yellow, mobile liquidrecovered. Nuclear magnetic resonance spectroscopy of the product showedthat it had the desired structure:

The 65 g. of distilled product obtained corresponds to a theoreticalyield of 75%. On the basis of the allyl sulfide reacted, the isolatedyield is 93%.

Elemental analysis.-Calculated for C H O PS (wt. percent}: C, 37.48; H,7.33; S, 33.36. Found (wt. percent): C, 38.50; H, 7.88; S, 33.60.

EXAMPLE 5 A mixture of 20.4 g. (0.2 mole) of allyl ethyl sulfide and39.2 g. (0.25 mole) of dimethyl dithiophosphoric acid was reacted in themanner described in the previous example. Nuclear magnetic resonancespectroscopy indicated that 44, 60 and 73% of the allylic groups reactedafter /2, 1 and 2 hours irradiation, respectively. After two hours thereaction mixture was worked up as described in the previous example.After the removal of solvent and unreacted started materials, 35 g. (67%yield) of crude, neutral product was obtained. On the basis of the allylethyl sulfide reacted this corresponds to an isolated yield of 92%. Then.m.r. spectrum of the product indicated the desired unsymmetricalstructure:

Elemental analysis.Calculated for C H O PS (wt. percent): C, 32.29; H,6.58; P, 11.89. Found (wt. percent): C, 32.31; H, 6.52; P, 10.53.

EXAMPLE 6 A mixture of 49.5 g. (0.25 mole) of allyl dimethyldithiophosphate and 31 g. (0.5 mole) of ethanethiol was irradiated for24 hours in the manner described in Example 4. Nuclear magneticresonance spectroscopy indicated that 77% of the allylic unsaturationdisappeared during the reaction period. A test of the mixture by litmusgave an acidic reaction indicating the formation of dimethyldithiophosphoric acid due to allylic reversal.

The crude reaction mixture was vacuum stripped to remove theethanethiol. Thereafter the product was dissolved in ether and washedwith aqueous sodium hydrogen carbonate solution to remove the acid.After drying the solution with sodium sulfate and removing the ether invacuo, 47 g. (72% yield) of neutral diadduct product remained.

Heating of the diadduct mixture at 105 C. at 0 .15 millimeters ofmercury pressure resulted in the distillation overhead of 12 g. of a1,3-bis-(ethylthio)-propane symmetrical diadduct. The residue (35 g.)consists of about equimolar quantities of another symmetrical diadduct1,3 bis-(dimethoxythiophosphorylthio)-propane and the desiredunsymmetrical diadduct,1-ethylthio-3-dimethoxythiophosphorylthio-propane. The approximate molarratio of the three diadducts is 7:525 in the above order.

The composition of the product mixture indicates poor selectivity to thedesired unsymmetrical 1,3-diadduct even though a two-fold excess of thepoorer hydrogen donor ethanethiol was used.

EXAMPLE 7 A mixture of 25.5 g. (0.25 mole) of allyl ethyl sulfide and47.4 g. of crude, dark dimethyl dithiophosphoric acid was heated for 36hours at about 50 C. Subsequent analysis of the reaction mixture byn.m.r. indicated that 60% of the allylic unsaturation had disappeared.The mixture was worked up as described in Example 4 to provide 43 g.(66% yield) of neutral, crude product containing allyl ethyl sulfide andtrimethyl dithiophosphate as minor impurities. These impurities wereremoved under 7X 10- millimeter of mercury pressure at 130 C. to secure31 g. (50% yield) of residual product.

The n.m.r. spectrum indicated that about 93% of the product possessedthe ionic adduct structure, i.e.

(CH O) PS CH (CH CH SC H (CH O PS CH (CH CH SCH (CH 2 upon heating.

10 EXAMPLE 8 A mixture of 23.2 g. (0.2 mole) of allyl isopropyl sulfideand 39 g. (0.25 mole) of dimethyl dithiophosphoric acid was reacted inthe manner described in Example 2 for 6 hours. After the removal of theunreacted reactants, 28 g. neutral, crude product was obtained, i.e.,50% of the theoretical yield. An n.m.r. spectrum of the productindicated that it was mostly A sample of the product was distilled withslight decomposition at 118120 C. and 3 millimeters of mercury pressureto yield a yellow liquid product.

Elemental analysis.Calculated for C H O PS (wt. percent): C, 35.02; H,6.97; P, 11.66; S, 35.06. Found (Wt. percent): C, 34.89; H, 6.96; P,11.24; S, 36.17.

EPQAMPLE 9 A mixture of 2.5 g. of allyl methyl sulfide and 5.3 g. ofdiethyldithiophosphoric acid was placed in a quartz reaction tube andirradiated with U.V. light at ambient temperature for a period of 31hours. The reaction mixture was then dissolved in ether and washed withan aqueous 5% Na CO solution to remove the unreacted acid. The solutionwas washed, dryed and distilled. The reaction product was analyzed andfound to have the structure:

EXAMPLE 10 A mixture of 16.8 g. of diethyldithiophosphoric acid and 18.4g. of allyl p-chlorophenyl sulfide was placed in a quartz reaction tubeand irradiated with ultraviolet light for a period of 3 days at ambienttemperature (approximately 20 C.). The reaction product was washed witha 5% aqueous Na CO solution and dried over anhydrous Na SO The productwas analyzed by nuclear magnetic resonance and found to be:

( 2 5 )2 2 2) a s s EXAMPLE 1 1 A mixture of 11.6 g. (0.1 mole) of allylthiolacetate and 37.2 g. (0.2 mole) of diethyl dithiophosphoric acid isreacted as described in Example 4 to yield the correspondingunsymmetrical diadduct of structure (C2H5O)2PS2CH2CH2CH2SCOCH3 EXAMPLE12 A mixture of 8.8 g. (0.1 mole) of allyl methyl sulfide and 15.5 g.(0.15 mole) diethyl monothiophosphoric acid is irradiated as describedin Example 4 to yield the unsymmetrical diadduct of structure:

(C2H5O) P O SCH CH CH SCH EXAMPLE 13 A mixture of 30 g. (0.10 mole) ofhexadecyl allyl sulfide and 33 g. (0.12 mole) of mercaptopropionic acidlauryl ester is irradiated at 50 C. to yield the correspondingunsymmetrical 1,3-bis-(substituted mercapto)- propane:

C H SCH CH CH SCH CH CO C H EXAMPLE 14 Samples of the mixed diadductsdescribed in Examples 4, 5 and 7-10 were tested for insecticidal,miticidal and nematocidal activity. These tests were performed by thefollowing general procedures:

Insecticide screening Mexican bean beetle tests--Lima bean leavessprayed on the dorsal and ventral surface are offered to ten larvae ofthe Mexican bean beetle (late second instar) for a forty-eight hourfeeding period. The feeding rate and mortality data are recorded as wellas foliage injury, if

11 any. The positive standards are 0.05% DDT and 0.1% Methoxychlor,which are commercial insecticides known to give 100% control at theseconcentrations.

Pea aphid tests--Adult pea aphids are sprayed and transferred to sprayedpea plants and held for forty-eight hour mortality determinations.Foliage injury, if any, is recorded. DDT at 0.05% concentration is usedas the positive standard.

Systemic insecticidal activity is evaluated by applying 20 ml. of 0.01%concentration of the sample to the vermiculite substratum of potted peaplants. Forty-eight hours after application the plants are infested withten adult pea aphids and mortality determination is made after fivedays. Demeton at 0.01% concentration, a commercial insecticide known togive 100% control at this concentration, is used as the positivestandard.

Miticide screening Spider mite testsLima bean plants are infested withfifty to one hundred adults of the strawberry spider mite, Tetranychusatlanticus, prior to testing. The infested plants are dipped into thetest material and held for five days. Adult mortality as well asovicidal action is noted. Aramite and Ovotran are used as positivestandards at 0.1% concentration. These latter compounds are commercialmiticides which are known to give l% control at this concentration.

The results of these tests are summarized in Table V.

12 activity of a compound formed with the process of the presentinvention was compared with the biological activity of a structurallyrelated dithiophosphate composition. In the first test, Disyston, aleading commercial pesticidal composition having the general formula:

were each tested for effectiveness against the Mexican bean beetle usinga routine WARE test. The spray concentration for 50% pest control forDisyston was 0.050%. In contrast, the spray concentration for 50% pestcontrol for the gamma-compound was 0.005%. This means that thecomposition formed according to the instant process has a killing powerequal to the commercially employed, closely related compound at theconcentration employed when Disyston is used.

EXAMPLE l6 Compounds prepared according to the present process werecompared for nematocidal activity with a structurally TABLE V Mortalityof insects Pen aphids Cone, Mexican Spider Product of example (hernicalstructure of product tested percent bean beetles (ontat-t Systemic mites4... (CzlI O)2P$(CII3MSC H 0.010 100 100 I00 100 1 0. 007 100 100 100100 S 0. 005 9U 90 90 5.. (CH3O)2PS(CH )3. Cglls 0.050 lUO lUO 100 100 lU. 010 90 100 100 7. (ClIgOhlSClI(Lll;)ClI;S C211 0.050 I) 100 90 0. 0100 100 50 8.. Cll Ohl S (Cllms (I'HCIIU 0. 025 40 100 100 83 l). 010 40I00 80 S 0. 005 I00 9.. [C:H O):l (Lli; C ll; 0. 050 I00 100 I00 100 iU. 025 100 100 S 0. 010 100 100 0. 005 100 (C;H5O);PO(CII;;;S(Il 0.010l) 0 0 EXAMPLE 15 A series of tests was conducted by the WisconsinAlumni Research Foundation (WARP) in which the biological relatedcommercial nematocide produced using other techniques. The compoundswere tested at 0.41 g. per gallon of soil equivalent to 100 lbs. perfour inch acre. Nemagon, a commercial nematocide, was used as a positivecontrol at a concentration of 40 lbs. per four inch acre. All sampleswere formulated into 10% dusts for mixture with soil.

Meloidogyne sp. nematodes were reared into tomato plant soil culture.The test soil was inoculated with infected soil and root knots frominfected tomato plants. Uninoculated soil was employed for control andphytotoxic effects. Chemical dusts were blended thoroughly with the soilin a V-shell blender. Four one-pint paper pots were used for eachtreatment with one tomato transplant per pot. After three to four weeksunder artificial lighting and overhead irrigation, the roots of theplants are examined for degree of root knot formation. Inoculatedcontrols normally have -100 root knots per plant. Per- 13 cent controlis recorded by comparison of the knot counts on treated and untreatedtomato plants.

The results of the test are set forth in Table VI below:

male mice, Swiss-Webster strain, weighing between 30 and 35 grams, wereused to determine the acute oral toxicity of the respectivedithiophosphates. The mice were housed The tests show that at a rate of100 lbs/acre a compound prepared according to Example 7 gave 100%control at rates of 40 and 100 lbs./acre. The compounds described inExample 9 produced a 95% control of the nematodes. The third compound,Disyston, a known and commonly used structural isomer of the othercompounds, prepared using other techniques, controlled nematodes only tothe extent of 50% at a rate of 100 pounds of chemical per acre and 30%at a rate of 40 pounds of chemical per acre. This evidences thatphosphate ester compositions having three carbon atoms between the twochain sulfur atoms, which compounds are formed according to the presentprocess, are suprisingly superior nematocides to known phosphate estershaving only two carbon atoms between the chain sulfur atoms of thecomposition.

EXAMPLE l7 Comparative field trials were made by the Wisconsin AlumniResearch Foundation against the potato flea beetle using theunsymmetrical diadduct product of Example 4, commercial Systox andMalathion. These materials were applied as emulsion sprays prepared froma formulation identical with that of commercial Systox at the rate of100 gallons/acre (point of run off) to 25 foot rows of potato plants atthe concentration of actual compound (lbs./acre) listed. Infestationdeterminations. were made prior to treatment and one, three and sevendays following treatment by making sweeps with a net (2 plants persweep) over the 25 foot row. The actual number of beetles counted andthe percent reduction of the infestation based on the untreated controlwere determined. No measurable rain fell during the test period. Theresults are listed in Table VII below:

TAB LE VIII 1350, Product of Structural formula mg./kg.

Example 7 (CH3O)21fiSCH2CH2 H2 C2H5 Commerce (Disyston) (CzH O)z"SCHzOHzSC2Hs The data set forth in Table VIII indicates that the medianlethol dosage of an ester compound prepared according to the presentprocess is times less than a closely related compound prepared usingother techniques.

The nematocidal, insecticidal and miticidal compositions produced withthis invention may be employed by either solid or liquid form. When usedin solid form, they may be reduced to an impalpable powder and employedas an undiluted dust or they may be admixed with a solid carrier such asclay, talc or bentonite as well as other carriers known in the art. Thecompositions may also be applied as a spray in a liquid carrier eitheras a solution in a solvent or as a suspension in a nonsolvent, such aswater. Typical solvents are organic compounds such as TABLE VIIReduction of beetle population, percent Field conc., Active compoundlbs/acre Days after application in 100 gal. Derivation Chemicalstructure water 1 day 2 days 3 days Examp1e4 (C H O)zP(S)SCH CHaCHaSCaHi0.5 92 89 67 Commercial control, Systox (Demeton)(C2H5O)2P(O)SCH2CH2SC2H 0.5 7 8 7 8 41 Commercial control, Malathion (CHO) P(S)SCHO0 C H {0. 5 Nil N11 N11 1 Nil Nil The results of Table VIIshow that the product of Example 4 was more eifective in the field thanSystox and Malathion. It was particularly interesting to observe thatthe product exhibited longer lasting pest control than the structurallyrelated Systox.

EXAMPLE 18 Another test series was conducted to compare the toxicitytoward warm-blooded animals of compounds prepared according to thepresent process with a structurally related dithiophosphate of Example7. In the tests, adult life. Suitable wetting agents include thesulfates of longchain alcohols such as dodecanol and octadecanol,sulfonated amide and ester derivatives, sulfonated aromatic and mixedalkyl aryl derivatives, esters of fatty acid such as the ricinoleicesters of sorbitol and petroleum sulfonates of C to C lengths. Thenonionic emulsifying agents such as the ethylene oxide condensationproducts of alkylated phenols may also be used. The compounds of thisinvention may also be admixed with carriers that are themselves activefungicidal and nematocidal compositions.

It is to be understood that the invention is not limited to the specificexamples which have been offered merely as illustrations and thatmodifications may be made without departing from the spirit of theinvention.

What is claimed is:

1. A process for preparing an unsymmetrical thiolallene diadduct whichcomprises contacting a monoadduct allyl sulfide having the structuralformula:

with a thiol compound having the structural formula RSH in the liquidphase for a time sufiicient to recover an unsymmetrical diadduct havingthe general formula:

wherein R and R are differing monovalent organic radicals having from 1to 30 carbon atoms and said RSH compound has a higher hydrogen donorability relative to the thiol corresponding to the RS radical of thesaid monoadduct allyl sulfide.

2. The process of claim 1 wherein R is selected from the groupconsisting of C to C alkyl radicals, C to C aryl radicals and C to Chaloaryl radicals and R is a dihydrocarbyloxythiophosphoryl radicalhaving the general formula:

X \ll 1 XO/ wherein X and X are C to C hydrocarbyl radicals.

3. The process of claim 1 wherein R and R are different radicalsselected from the group consisting of C to C alkyl radicals, C to C arylradicals, C to C haloaryl radicals, acyl radicals having the generalformula:

wherein Z is a C to C hydrocarbyl radical, anddihydrocarbyloxyphosphoryl radicals having the formula:

wherein X and X are C to C LB hydrocarbyl radicals and Y is selectedfrom the group consisting of sulfur and oxygen atoms.

4. The process of claim 3 wherein Z, X, and X are C to C alkyl radicals.

5. The process of claim 3 wherein the said alkyl radicals have from 1 to10 carbon atoms.

6. The process of claim 3 wherein said reaction is conducted at atemperature ranging from l00 to 150 C. in the presence of a free radicalinitiator.

7. The process of claim 6 wherein said reaction is conducted in thepresence of a molar excess of said thiol.

8. The process of claim 7 wherein said reaction is conducted at atemperature ranging from 0 to C.

9. The process of claim 6 wherein said free radical initiator isultraviolet light.

10. The process of claim 6 wherein said reaction product contains atleast about 50 mole percent of the desired unsymmetrical adduct.

1 6 11. The process of claim 1 wherein R is selected from the groupconsisting of C to C alkyl radicals, C to C aryl radicals, C to Chaloaryl radicals and R is selected from the group consisting of acylradicals having the general formula:

wherein Z is a C to C hydrocarbyl radical anddihydrocarbyloxythiophosphoryl and dihydrocarbyloxyphosphoryl radicalshaving the formula:

wherein X and X are C to C hydrocarbyl radicals and Y is selected fromthe group consisting of sulfur and oxygen atoms.

12. The process of claim 11 wherein Y is a sulfur atom.

13. A process for preparing an unsymmetrical thiolallene diadduct whichcomprises contacting a thiol compound having the formula RSH with amolar excess of allene in the liquid phase in the presence of a freeradical initiator for a time sufiicient to recover a monoadduct allylsulfide having the structural formula:

and reacting said monoadduct with a thiol compound having the structuralformula RSH in the presence of a free radical initiator for a timesufiicient to recover a product containing at least about 50 molepercent of an unsymmetrical adduct having the general formula:

wherein R and R are differing C to C organic radicals, said RSH compoundpossessing superior hydrogen donor ability relative to said RSHcompound.

14. The process of claim 13 wherein said reactions are conducted attemperatures ranging from to C.

15. The process of claim 14 wherein R and R are different radicalsselected from the group consisting of C to C alkyl radicals, C to C arylradicals, C to C haloaryl radicals, acyl radicals having the generalformula:

wherein Z is a C to C hydrocarbyl radical, anddihydrocarbyloxythiophosphoryl and dihydrocarbyloxyphosphoryl radicalshaving the formula:

wherein X and X are C to C hydrocarbyl radicals and Y is selected fromthe group consisting of sulfur and oxygen molecules.

16. The process of claim 15 wherein the molar ratio of allene to saidRSH compound varies from 2:1 to 10:1.

17. The process of claim 16 wherein said reaction between saidmonoadduct allyl sulfide and RSH is conducted in the presence of a molarexcess of said RSH compound.

18. The process of claim 17 wherein R and R are selected from the groupconsisting of C to C alkyl groups, C to C aryl groups, C to C haloarylgroups,

dihydrocarbyloxyuhosphoryl and dihydrocarbyloxyphos- References Citedphoryl groups having the structural formula: L Organic Chemistry VOL 28(August 1963) Pages X0 Y l95256.

X10 5 HOWARD S. WILLIAMS, Primary Examiner wherein X and X are C to Calkyl radicals and Y is a sulfur atom. 204158H'E, 162, 162HE; 260-609;424215 19. The process of claim 18 wherein said reactions are conductedat a temperature varying from about 0 to 50 C. 10

